Introducing EngineLabs’ Newest Project Engine: The LS5.0

For most people, planning out an engine build involves utilizing the most proven techniques and components, in order to achieve an expected outcome. But sometimes, you want to do something simply because it isn’t commonly done. Whether it’s simply a proof-of-concept build, or aimed at answering a specific question, going outside of the box with an engine build has risks, but also an equal or greater chance at reward.

Since this is EngineLabs, and a laboratory suggests experiments, we’ve decided to take on a project via a road less traveled. Actually, “road” suggests that enough people have traveled a path enough to engineer a road. At the very best, this is a goat trail. But, that’s not to say we are going into this haphazardly. In fact, this engine project has been brewing for over two years as the idea has gone from garnering scoffs to raised eyebrows.

Genesis Of The Project

Let’s face it, the LS platform has been built into a million different combinations. It is probably the most popular engine platform in this country right now and enjoys a huge amount of aftermarket support. So doing something different isn’t the easiest thing in the world. The spark for this fire (whether it’s a controlled burn or raging dumpster fire is yet to be seen) came about with the original LS vs. Coyote Budget Shootout.

Right off the bat, the rules were implemented that it would be a 6.2L LS3 vs. a 5.0L Coyote, immediately putting the Blue Oval powerplant at a displacement disadvantage. That displacement disparity was further exacerbated in the second, supercharged round of the LS vs. Coyote Shootout, where the LS engine displaced a whopping 427 cubes to the Coyote’s 302.

These are the two engines of the original LS vs. Coyote Budget Shootout that started this whole thing. One of the largest gripes we heard on the internet was about how unfair it was that the LS3 was 1.2 liters larger than the Coyote. That ultimately led to our “what if.”

There was no arguing the disparity in engine sizes in both tests, but both times, the critics clamored “If the LS wasn’t so big, the Coyote would have won!” Now, there is some merit to that argument, since in both cases, Ford’s dual overhead cam engine made more power per-cubic-inch than its pushrod competitor. It was enough that we enlisted COMP Cams’ DynoSim 5 software to run some tests of our own.

In that article, you can see that pitting a virtual  5.0-liter Coyote engine against a virtual 5.0-liter LS provided numbers far closer than anyone we talked to would have guessed. That article also lit the fuse to build the modeled engine in real life. How would a 5.0-liter LS engine, built in the spirit of the original rules, perform in real life?

Initially, we’ve found people fall into two camps. Camp one says, “if displacement is the same, they will probably perform the same.” Camp two is of the mind that because one is a pushrod engine and the other is an overhead cam engine, the two engines will perform wildly differently. If we take into account the power-per-cubic-inch numbers from the previous tests, we certainly have our work cut out for us to get the LS5.0 to match the Coyote’s results.

But, let’s be clear right out of the gate; while yes, we’d love to make more power than the Coyote did in the first series, this project isn’t about one singular dyno result. Rather, this is about exploring the theories and reasoning behind why we get the results we do. Simply put, it’s about the journey rather than the destination. So to answer the inevitable “why” questions — because we’ve never seen it done this way before, and are curious.

This was the first step in this project becoming a reality. We modeled the LY2 in DynoSim 5 software, using flow numbers for the 799 heads we found on the internet. One of the early steps we plan to undertake is to put our actual cylinder heads on the flowbench to see if they match those numbers.

In the coming articles, we’ll be bringing you a lot of information about this project. Far more than a traditional engine build. We’re partnering up with Ben Strader at EFI University for a lot of the science of the build, because besides being an incredibly smart guy who knows his way around an LS engine (Spinal Tap, anyone?) he’s great at communicating that knowledge to others. It’s almost like he’s a teacher or something.

The Plan And Progress So Far

In the article we linked above, where we used DynoSim 5 to model a 5.0-liter LS engine, we laid out a build plan. In fact, we won’t be straying much from that plan at all in the actual build. As we said in that article, we’d start with a 4.8L LS variant, the Gen-IV LY2 in particular. As we started looking for an LY2 engine locally, we found that not only are 4.8L LS engines not as easy to find in northern Arizona as they are in other parts of the country, they aren’t nearly as inexpensive, either.

After a couple of months of searching with no luck, we decided to reach out to some friends to see if they had any leads. One of those we reached out to was Josh Stahl at Reviva Corporation. We’ve brought you several articles on Reviva’s line of high-performance crate engines in the past, so you’re probably familiar with the name. However, there’s another side to the business, under the Reviva name for light-duty gas and diesel as well as Pilot Engines for medium- and heavy-duty diesel applications.

Our Gen-IV 4.8-liter LY2 truck engine core came to us by way of Reviva Corporation/Pilot Engines. Despite what the internet says, LS engines (especially Gen-IV 4.8Ls) aren’t overflowing every scrapyard, and things were starting to look bleak until Reviva came to our rescue.

Reviva and Pilot Engines remanufacture a lot of engines for a lot of customers, and as such, have a solid supply of core engines on hand. After talking to Josh, he did a quick check and sure enough, he had an LY2 core in the warehouse. Good news for us, since that means we didn’t have to deal with eBay (which was getting dangerously close to becoming a reality) or buying multiple cores and components separately to end up with the factory parts we wanted to start the project with.

In short order, the LY2 was on a truck from Minneapolis, Minnesota to sunny Arizona and we were off to the races. As soon as it arrived, we started tearing it down to get ready to send it to the machine shop. As we outlined in the previous article, we’ll need to open the bore up to 3.858 inches to achieve the target displacement. That should be no problem as LS1-bore iron blocks are a relatively common thing, and we’re going to .040 inch under a stock LS1 bore. Other than that, it should be just a minor cleanup to the block.

One of the first things we did was check out our core engine's specs to see if it had been rebuilt previously. While the bores measured .006-inch over stock, indicating a slight rebuild, the chambers actually measure slightly higher than the 64cc spec, which means that the heads haven't been machined previously.

Why An LY2?

We wanted the LY2 engine for several reasons. First, the LY2 is the only Gen-IV 4.8L variant without AFM. Another big reason is the OEM cylinder heads. The LY2 comes with the 799 cylinder head standard, and will make for a great performance base on which to build, as they have great ports and already have a valve configuration optimized for a small bore. We’ll be diving deep into the bore size versus valve size issue later on in the project.

Additionally, since the LY2 is a Gen IV engine, we get the 58x reluctor wheel, which will benefit us in the upper RPM range, and we are planning on turning this engine pretty hard in order to keep up with the Coyote and its rev-happy design. Speaking of the Gen IV upgrades, we also get the desirable Gen IV rods. However, in the Gen IV 4.8L engines, we get the longer 6.275-inch rods (the same length as found in the Gen III 4.8L engines) so that the factory doesn’t need to run different compression heights between the 4.8-liter and 5.3-liter pistons.

One of the benefits of the Gen-IV LS engine is the 58x reluctor wheel. It offers over twice the resolution of the 24x which will come in handy in the upper RPM ranges. However, we won’t be spinning it hard enough to encounter Hall-effect saturation.

That said, that 6.275-inch connecting rod throws a bit of complication into the rod and piston selection. However, since we’re going to need to go with a custom piston due to the oddball bore size and to get to the target 11-ish to 1 compression ratio, adding 0.150-inch of compression height from the common 5.3L piston designs shouldn’t be too much of a hassle, if we decide to go with 6.125-inch aftermarket rods.

While the original simulation predicted the combination would be right at the 500 horsepower mark, there have been several critical developments since that article has been released, like Holley’s line of Hi-Ram intakes, and COMP Cams’ Low-Shock Technology for the valvetrain, which is resulting in some pretty impressive stability and power increases.

In fact, we’ve already been in contact with Billy Godbold about trying to accurately model some of the LST lobes, and we’re probably going to need to actually do some dyno testing, since the software was never built with those profiles in mind (yes, the new designs are really THAT revolutionary).

While the information on the internet regarding Gen IV 4.8-liter rod length is murky at best, we can confirm that these are, in fact, the longer 6.275-inch rod length of the Gen III 4.8Ls, but in the Gen IV rod. If you are wondering how we measured a 6.275-inch length with six-inch calipers, that’s easy. You take half the big end bore (2.100 inches) and half the little end bore (0.945 inches) and add those to the measured center section (4.753) to get your center to center distance.

Another thing we’re aiming for in this project is to stay within the original LS3 vs. Coyote Budget Shootout’s budget constraints of a total outlay of $9,999. We’re genuinely not worried about that, due largely to the fact that we are using so many factory parts compared to the original LS3 build, and the fact that using crazy, exotic parts isn’t really in the spirit of this project. But, if we do happen to go over, no biggie, as this isn’t any kind of official competition.

With the block torn completely down, it’s time to head to the machine shop to get a much-needed cleaning, a quick align bore with the new ARP Main Stud Kit installed, and have the bores opened up to our final size.

So be sure to follow along as we get this project series rolling along. The first article you should see after this one will cover the machining of the block. While the junkyard LS has really changed the face of the performance industry, we’re going to be giving the factory block the full treatment, not often seen on LS blocks. This project is an open book and we’ll be talking about every step along the way, no matter where it takes us. We’re in this one for the science of it.

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About the author

Greg Acosta

Greg has spent fifteen years and counting in automotive publishing, with most of his work having a very technical focus. Always interested in how things work, he enjoys sharing his passion for automotive technology with the reader.
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